I am not good with scripts and I am wondering if any one can share a script that allows the database to back up to an external drive each and every time I close the database
Use on last window close then save a copy as to your desired location. I mean an OnLastWindowClose script trigger in file options.
Get FileMaker Server and use the scheduled backups
Have a look at this article on FileMaker Hacks for a start:
Retrieving data ...